A multi-coordinate probe having several support points is discussed in DE-PS 27 42 817. A V-groove is located concentrically around the probe head axis in a measuring dish which is connected with the probe pin or feeler. A V-groove, which also extends in an annularly-shaped fashion, is located so as to be opposite to the first groove in the housing of the probe. Several spheres or balls are bonded into each one of these V-grooves, wherein each bearing support is constituted by the cooperation of three spheres. The spheres are located opposite each other in such a manner, that each sphere in the measuring dish contacts two spheres in the housing of the probe.
In order to assure that the desired contact occurs between the spheres, one allows the balls to roll freely into their grooves during the set-up or adjustment process, wherein they then align themselves as a result of the spring force exerted upon the measuring dish and the curvature of the spheres. Subsequent to this adjustment, a bonding agent or adhesive, inserted into the V-groove, is cured or hardened and retains the spheres in the V-groove.
Since every sphere adjusts itself in a circumferential direction as a function of all other spheres, the frictional forces during the set-up or adjustment process are added and thus the force required for the adjustment is increased. Further, it has been seen that non-uniform relatively large bonding gaps form between the individual spheres and the V-groove whereby unequal elastic properties and rigidity of the individual bearing or support points are produced. The large bonding gaps, especially in the circumferential direction of the V-grooves, causes a displacement or migration of the spheres or balls during temperature changes as well as due to the effects of humidity.
A multi-coordinate probe is known from the DE-PS 35 08 396, wherein each bearing or support point is individually adjustable independently of the other support points. Each support point is formed by a sphere and an adjustable cylindrical member with a V-groove. Each cylindrical member is rotatable around its axis and axially displaceable, so that the V-groove can be aligned with the associated sphere. It is disadvantageous in this arrangement, however, that each bearing or support point is only formed by two points of contact between a V-groove and a sphere. This point contact results in a relatively low rigidity of the individual support points.
In order to increase the rigidity, a multi-coordinate probe was proposed in DE-PS 36 40 160, wherein each bearing or support point was formed by an axially and radially adjustable bearing and counter member. The contact zones of the respective surface regions of the support or bearing members and the surface regions of the associated counter members, respectively, form a circular line. The adjustment of a cone-shaped bore with respect to a sphere is performed by means of a double eccentric cam. The cone-shaped bore is placed externally of the rotational axis of a rotatable cylinder. This cylinder is eccentrically supported in a rotatable receiving cylinder. For adjustment, the inner cylinder and the receiving cylinder must be rotated against each other and displaced in an axial direction. This probe, however, requires greater fabrication efforts.